Apparatus for making nail strips

ABSTRACT

A nail strip in the form of an elongated band of durable material formed from a blank, having in cross-section taken substantially perpendicular to its longitudinal axis, an elongated shank portion, a tip portion at one end of the shank portion and an enlarged head portion at the other end of the shank portion is formed by producing a series of spaced-apart, straight, parallel grooves in opposite faces of the blank, the grooves on either side of the blank being disposed opposite each other. The grooves define in the band a multiplicity of individual nails, the nails being connected by webs of material at the bases of the grooves. The cross-sections of the webs of material joining the nails are such that an end nail in the strip may be sheared off by the application of a predetermined driving force. The nail strip is particularly well suited for use in a mechanical, electrical or pneumatic hammer that is provided with a magazine to receive the strip and deliver the nails to the driving element.

Unite States Patent 1 1 1111 3,758,901 Wainman 1 Sept. 18, 1973 APPARATUS FOR MAKING NAIL STRIPS Primary Examiner-Richard J. Herbst Assistant Examiner-E. M. Combs l [75] Inventor Roger wamman Brussels Be glum Attorney-Brumbaugh, Graves, Donohue & Raymond [73] Assignee: Industrial & Merchandising Services S.A., Brussels, Belgium 221 Filed: Sept. 22, 1971 [57] ABSTRACT [21] APP] No: 182,889 A nail strip in the form of an elongated band of durable material formed from a blank, having in cross-section Relfled Appllcfllon taken substantially perpendicular to its longitudinal [62] Division of Ser. No. 35,863, May 8, 1970, abandoned. axis, an elongated shank portion, a tip portion at one end of the shank portion and an enlarged head portion [52] U.S. Cl 10/29, 10/35, 10/53, at the other end of the shank portion is formed by pro- 10/61 ducing a series of spaced-apart, straight, parallel [51 Int. Cl. 821g 3/26 grooves in opposite faces of the blank, the grooves on [58] Field of Search 10/29, 32, 33, 34, either side of the blank being disposed opposite each 10/35, 40, 41, 42, 53, 54, 61, 70; 206/56 AB, other. The grooves define in the band a multiplicity of 56 DF; 227/93 individual nails, the nails being connected by webs of material at the bases of the grooves. The cross-sections [56] References Cited of the webs of material joining the nails are such that UNITED S S PATENTS an end nail in the strip may be sheared off by the appli- 457 583 8/1891 Goldie 10 34 cation of driving 9 Strip 39951583 7/1963 is particularlywell suited for use in a mechanical, elec- 3 09 ]g7 11/1963 trical or pneumatic hammer that is provided with a 3,234,572 2/1966 magazine to receive the strip and deliver the nails to the 3,348,669 10/1967 driving element.

2 Claims, 12 Drawing Figures Pmmmsmam 3,758,901

SHEET 1 0F 2 I INVENTOR ROGER WAINMAN APPARATUS FOR MAKING NAIL STRIPS This application is a division of Ser. No. 35,863, filed May 8, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a nail strip of the type adapted to be used in powered nail-driving equipment, such as a mechanical, electro-mechanical, or pneumatic hammer, and to a method of and apparatus for manufacturing the nail strip.

Various types of mechanical, electro-mechanical and pneumatic nail-driving devices, such as hand-operated nailing guns and nail-driving components of various types of machines, have been used for quite some time. Devices of this type usually employ strips of nails that are loaded into a magazine that delivers them automatically, such as by spring-loading the strip, to the driving elements of the device. The nails are normally connected to each other in a manner that makes the strip substantially self-supporting and facilitates loading the magazine but that permits each nail to be separated from the strip upon application of a driving force ex erted by the driving element of the device. Frequently, the nail strips employed with equipment of the type referred to are manufactured individually and are then interconnected into a strip, sometimes by gluing them together using special machines or by providing a band of material, such as plastic or paper, to interconnect them. The equipment used to take individual nails and put them into a strip is frequently complicated and in any event necessitates expenditures over and above the cost of manufacturing the individual nails. Consequently, it has been proposed to manufacture nail strips directly, that is, by a process that results in a strip and does not involve the creation of separate nails that are later connected together.

One proposed technique of producing a nail strip involves simply cutting pieces out of a band, thereby leaving tapered nail elements that are interconnected at their heads. Such as process, however, involves substantial quantities of waste pieces that are cut out of the strip, thus resulting in the loss of material that has little value other than as scrap. Other techniques have in volved forming cuts in bands of metal to produce two groups of interconnected nails, each group being in the form of a comb-like strip and having the heads of the nails connected together. In both of the aforementioned techniques, the nails are connected only at their heads and are usually connected by a thickness of material substantially equal to the thickness of the original strip. Inasmuch as the nails are connected only at their heads, there is significant opportunity for them to be knocked out of alignment, thereby making it more difficult to load the magazine, or for the nails to be knocked out of alignment and to mistrack upon being driven. Also, the nails usuallyhave only small heads and may not be adapted for certain nailing purposes, although it has been proposed to provide relatively large-sized heads by bending over tabs at the head edge of the strip.

It has also been proposed to manufacture a strip of nails or tacks by a succession of forging operations that produce in a strip of material a desired nail configuration and provide an interconnection of the nails or tacks at their heads. The strip is conducted through a series of forging dies that gradually work the material into the desired shape. Equipment of this type employing punching elements has also been suggested. As with the forms of nail strips referred to above, the nails are interconnected at the heads. Moreover, the equipment is quite elaborate, and the technique involves a number of successive operations.

SUMMARY OF THE INVENTION There is provided, in accordance with the invention, a nail strip and a method of and apparatus for manufacturing it that overcome various disadvantages associated with the nail strips and techniques proposed heretofore and that offer important advantages in their own rights. More particularly, a nail strip, in accordance with the invention, is in the form of an elongated band of durable material having in cross-section, taken substantially perpendicular to the longitudinal axis of the band, an elongated shank portion, a tip portion at one end of the shank portion, and an enlarged head portion at the other end of the shank portion. Preferably, the cross section of the band is substantially symmetrical about a center line extending axially of the shank portion. Individual interconnected and juxtaposed nails are defined in the band by substantially uniformly spaced-apart, straight, parallel grooves fonned in each side surface of a blank from which the nail strip is formed. The grooves on either side of the band are located substantially opposite each other and transect the shank, tip and head portions.

The grooves are of a depth such that they leave only a thin web or webs of material between them, such webs of material serving to interconnect the adjacent nails in the strip. The web of material may extend nearly the entire length of the nails or may be interrupted to the extend that there remains between the nails only one relatively short web or two or more spaced-apart webs of material. However, it is advantageous to form an interconnecting web structure that provides, in effect, at least two connecting points spaced along the length of the nail, thereby to restrict the opportunity for the nails to be knocked out of alignment and to ensure against the nails being accidentally severed in handling. The total cross-sectional area of the web structure between the adjacent nails is established with relation to the equipment with which the nails will be used so that the driving force of the equipment is sufficient to shear the web and enable the end nail of the strip to be driven in the desired manner. The amount of web material and the configuration of the web structure may vary widely, depending upon the type of material for the strip and the equipment in which it will be used.

The nail strips may be made of various materials, such as steel, copper, aluminum, and even plastic, and the particular configuration of the nail strip may vary widely depending upon the material used and the end use of the nail strip.

The method of manufacturing the nails involves, basically, only a single-step operation, namely that of forming in the opposite surface of the blank the series of spaced-apart, oppositely located grooves that define the nails in the strip. The shapes and depths of the grooves are determined by the design of the dies that are used to form them, and the design of the dies, in turn, depends upon the desired configuration of the nails and heads. Preferably, the grooves are formed by a combined cutting and forging operation and employing dies having generally wedge-shaped cutting and forming surfaces. While such dies cut into the material to some extent, they also produce a substantial amount of permanent deformation of the material in a manner similar to forging or coining.

Inasmuch as the nails of the nail strip, according to the invention, embody enlarged head portions, i.e., portions larger than the shank, the dies used to form the grooves include two sets of cutting and forming surfaces, each set of cutting and forming surfaces constituting a wedge-shaped section of the die. The included angle between the faces of the wedge-shaped portion of the die that forms the groove in the shank and tip portion of the nails is substantially larger then the included angle between the faces of the wedge-shaped portion that forms the grooves in the heads of the nails. Consequently, the percentage displacement and deformation of material in the shank and tip portions of the blank is greater than the percentage displacement and deformation in the head portion. However, inasmuch as the head portion has a greater cross-section, the total displacement of all portions of the blank is substantially uniform. Thus, this aspect of the invention enables the strip to be formed in a substantially straight band rather than in a curving configuration that would be created if uniform wedge-shaped dies were employed.

DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference may be made to the following description of exemplary embodiments, taken in conjunction with the figures of the accompanying drawings, in which:

FIG. 1 is a pictorial view of a length of a blank from which one embodiment or nail strip is formed;

FIG. 2 is a pictorial view of a nail strip manufactured from the blank of FIG. 1;

FIG. 3 is a view looking down on the top edge of a blank and depicting the method of the invention schematically;

FIG. 4 is a view, also schematic, illustrating an alternate form of dies for producing a slightly modified configuration of nail strip, the view being taken looking at the end of a' nail in a strip and at the side surfaces of dies;

FIG. 5 is. a top view looking down on the head edge of a nail strip and depicting generally schematically an alternative type of forming mechanism;

FIG. 6 is a side view in elevation of a portion of an apparatus employed to manufacture a nail strip.

FIG. 7 is a top view of the apparatus illustrated in FIG. 6, the view being in section taken generally along the lines 7-7 of FIG. 6 and in the direction of the arrows;

FIG. 8 is an end view of the apparatus of FIGS. 6 and 7 taken from a point to the right of FIG. 7 and showing a cutting device for severing a group of nails from a continuous strip;

FIG. 9 is a pictorial view of an exemplary form of die for manufacturing the nail strip shown in FIG. 2;

FIG. 10 is a top view, FIG. 11 is a side elevational view and FIG. 12 is a front-end view of the die of FIG. 9.

DESCRIPTION OF EXEMPLARY EMBODIMENTS In FIG. 1, the reference numeral designates generally a blank from which one form of nail strip, according to the invention, is manufactured. Although the precise configuration and dimensioning of the nail strip will, of course, vary, depending on the end use of the nails and the driving device in which they are used, the blank 20 will be pre-formed to include, in cross-section taken in planes substantially perpendicular to the axis of the blank, a shank portion 22, a tip portion 24 at one end of the shank portion and an enlarged head portion 26 at the top end of the blank. The blank may be manufactured from various materials, such as steel, aluminum, copper or plastic, again depending upon the requirement for the nails, and may be produced by rolling, extruding, forging, casting and the like, depending upon the material and end use. For example, a steel nail strip may be manufactured from a cold-rolled strip of relatively ductile steel. In general, the nail strips should be manufactured from a relatively ductile and malleable material, inasmuch as the method of forming it is, at least in part, a forging or coining operation. If a brittle material were used with the method of the invention, it would be difficult, at best to form the individual nails in the strip without shearing or fracturing them away from the strip form.

In the form shown in FIG. 1, the shank portion 22 of the blank is of substantially uniform width, the tip is tapered to provide a sharp point, and the head is formed by surfaces that diverge upwardly and outwardly from the shank and provide the greatest dimension of the section at the uppermost end of the head portion.

Referring next to FIG. 3, the blank 20 is formed into the nail strip by producing in each of the side surfaces of the blank a multiplicity of uniformly spaced-apart, parallel, straight grooves 28 (see also FIG. 2). In the embodiment, the grooves are located in planes perpendicular to the axis of the blank, and the grooves in each side of the nail strip, which is designated generally in the drawings by the reference numeral 30, are located opposite each other, thereby to define a multiplicity of interconnected, juxtaposed individual nails 32. In the embodiment illustrated in the drawings, the grooves are substantially v-shaped in cross-section and are of a depth such that a thin web 34 of material is left between each pair of opposite grooves, the web 34 extending substantially continuously over the length of the nails and serving to interconnect adjacent nails. The thickness of the webs 34 is such that the strip 30 is self-supporting and is able to withstand handling and loading into the equipment with which it is used but is readily sheared upon the application of a driving force to the end nail of the strip as it is delivered to the driving component of the apparatus.

FIG. 4 illustrates a modified form of nail strip 30a in which the blank and the nails produced are of substantially the same general cross-section as those of FIGS. 2 and 3 but in which the interconnecting webs between adjacent nails are constituted by spaced-apart small webs 34a of generally round form in section. It will be apparent to those skilled in the art that the embodiment of FIGS. 2 and 3, on the one hand, and the embodiment of FIG. 4, on the other hand, represent the opposite ends of a spectrum of possible arrangements for the interconnecting web structure by which individual nails are attached to each other to form the nail strip. For example, a single web extending only part of the length of the nails may be employed, or a series of webs having slots between them but of generally elongated form and of varying numbers may likewise be created. It will also be readily apparent that the various forms of web structure may be produced by varying the configuration of the ends of the dies employed to form the grooves.

More particularly, referring to FIG. 3, the grooves 28 are formed in the blank by a pair of reciprocating cutting and forming dies 36 that are mounted for movement along a common plane substantially perpendicular to the axis of the blank 20 and are driven in reciprocating motion by appropriate driving devices 38 (illustrated schematically). For example, the driving devices 38 may be cam mechanisms that provide an appropriate reciprocating motion to the dies 36 to move them conjointly inwardly and outwardly in inphase relation, thereby to cause them to act substantially uniformly on opposite sides of the blank 20.

As described in somewhat more detail below, the dies 36 appropriate for forming a nail strip in which a web of material extends substantially continuously the entire length of the nails, has a point that is straight and uninterrupted, so that the degree of penetration of both the dies into the blank is uniform. To produce a modified form of web structure, as for example depicted in FIG. 4, the dies 36a have generally semi-circular cutouts 37a. The dies for making the embodiment of FIG. 2, as will be apparent to those skilled in the art, do not come together, thereby leaving the thin web of material, whereas dies for making the embodiment of FIG. 4 do come together or at least approach each other closely enough such that the material between the webs 34a is severed, the cutouts 37a, however, leaving the webs intact.

FIG. 5 shows a modified approach to forming the grooves in the blank 20. In particular, the grooves 28 may also be produced by rotary-type die elements 40 that rotate on shafts 42 in the directions indicated by the arrowed lines. Each rotary die element is circular and has a series of cutting and forming teeth 44 along its perimeter, the dies being located and being rotated in synchronism so that the teeth enter and form the grooves and also feed the blank 20 in the direction indicated by the arrow through the forming apparatus. As with the embodiments illustrated in FIGS. 3 and 4, the configuration of the teeth 44 will vary, depending upon the configuration of the interconnecting webs to be left between the nails in the strip.

Referring next to FIGS. 6 and 7, the apparatus for manufacturing the strip 30 from a blank 20 includes a combination guide and holding bar (see also FIG. 8) that is formed with a longitudinally extending slot 52 having a cross-section substantially matching the crosssection of the blank 20 but having a clearance so that the blank 20 may be slided longitudinally through it. The member 50 is provided with a top cover 54 that closes the upper end of the opening and prevents the blank from moving vertically. The guide 50 further includes side openings 56 at opposite locations on both sides that allow the dies 36 to operate on the blank. Supplemental holding elements in the form of plates 58 secured to the member 50 and provided with inwardly extending flanges 60 that engage opposite sides of the blank at locations closely adjacent the place where the grooves are formed further assist in holding the blank in position as each grooving operation is performed.

As mentioned previously, the forming of the grooves involves a combination of cutting and coining or forging in which a part of the formation of the grooves results from permanent deformation of the material. Consequently, there is a tendency for the material on either side of the plane where the grooves are being formed to be urged outwardly in a longitudinal direction, the blank being urged back to the left (with reference to FIG. 7). Therefore, a spring-loaded retainer dog 61 is provided to prevent the blank 20 from being driven backwardly (to the left). In the meantime, the portion of the blank that has already been formed in the nail strip 30 is substantially free to move to the right and allow the deformation or deflection of the material to occur freely as the dies from the grooves.

Any suitable apparatus for supplying the blank material to the groove-forming apparatus may be employed. For example, the blank 20 may be supplied in the form of a long strip wound in a coil, or it may be supplied in the form of individual strips of a convenient length. The feeding apparatus may be of any conventional form, for example, cam-operated feed dogs (not shown) operated in controlled synchronism with the operation of the dies 36. The feed apparatus advances the blank 20 longitudinally a predetermined distance equal to the width of each nail between each stroke of the dies 36 and retracts during the operation of the dies to be in readiness for the next feeding operation. In the event of multiple pointed dies being used, for example two or more points, then the feed mechanism would advance the strip the pitch of two or more nails. Thus, the blank 20 is repeatedly advanced a predetermined distance, the dies moved inwardly to form the grooves while the blank is held stationary, the dies are retracted and the feed dogs returned for the next cycle.

Although it is appropriate for the nail strip to be wound into a coil and supplied in that form for ultimate use, particularly when the equipment with which the nail strip is used is a machine-operated, as opposed to a hand-operated hammer device, the equipment may further include, as illustrated in FIGS. 6, 7 and 8, a cutting device 66 for severing predetermined lengths of nail strip from the relatively long strip produced by the equipment. An appropriate device located downstream from the forming equipment, such as a photocell device 68, may be used to determine when a given length of nail strip has been produced. A signal generated by the photocell device 68 controls the operation of the cutter device 66. One form of cutter, as best shown in FIG. 8, includes a pivoting cutting blade 70 mounted on a pivot pin 72 and driven by an actuating rod 74, the rod in turn, being operated by a solenoid, a pneumatic cylinder, or any other suitable mechanism, that pivots the blade to move the cutting portion of the blade across the strip and sever a piece of predetermined length and then restore it to its rest position. A spring-loaded backup plate 76 assists in holding the free end of the blank in position as it comes from the equipment.

Inasmuch as the head portion 26 of the blank is enlarged, relative to the shank and tip portions, the amount of material, on a proportionate basis, to be displaced is greater in the head than in the shank and tip portions. Consequently, if a die having a uniform wedge-shaped cutting and forming portion were used, the amount of material displaced in the head portion would be greater than the amount of material displaced in the shank portion, thereby resulting in the strip being bent into a curvature. Accordingly, the apparatus, according to the invention, preferably utilizes cutting and forming dies 36 that are constructed to compensate for the disproportionate amount of material to be dis placed as the grooves are formed in a type of nail having an enlarged head.

Referring to FIGS. 9 through 12, inclusive, an exemplary form of die 36 includes two wedge-shaped cutting and forming tip portions 80 and 82 of different configurations in that the included angle between the faces of the lower portion 80 is substantially greater than the included angle between the faces of the upper portion 82. The lower portion 80 forms the groove in the shank and tip portions of the nail strip, and the upper portion 82 forms the groove in the head portion of the strip. Because of the greater included angle in the lower portion 80, it displaces a proportionately greater amount of material than does the upper portion 82. Accordingly, the absolute amount of displacement of the material in the shank and tip portions is substantially equal to the amount of material displaced in the head portion, with the result that the nail strip, as it is forced forward from the cutters, is substantially straight. The relationship between the angles of the portions 80 and 82 may be varied to accommodate to different materials and different configurations of grooves.

It is apparent, particularly from FIGS. 11 and 12, that the upper and lower faces of the die 36 are nonparallel. This is merely to ensure that an operator will not install a die in an inverted position with the possible result of damage to the equipment by forming the nails improperly upon start up.

It is usually desirable to provide blunted dies, that is, dies having an end or edge at the apex of each wedgeshaped working tip that is ground to a radius of something in the order of 0.25 millimeters. If the dies had sharp edges, the separating forces developed at the tip ends would with most material, be sufficient to generate excessive tensile stresses in the material with the result that even though the dies may not come together, the stresses generated would be sufficient to fracture the material and sever the individual nails. The radiussed dies produce lesser stress concentration and restrict the possibility of severing individual nails.

Thus, there is provided, in accordance with the invention, a method of and apparatus for manufacturing nails embodying, basically, only a single step and employing equipment that may be of relatively low cost, involve only a limited number of moving parts, and is capable of relatively trouble-free operation. The nail strips of the invention provide the advantage of a desirable configuration, particularly in that they include an enlarged head that is desirable for good holding ability, and also offer advantages from the standpoint of magazine holding and feeding in both hand-operated and machine-operated nailing equipment and of joinder throughout their length or at spaced portions, thereby restricting the opportunity for the nails to be knocked out of alignment and thus create difficulty in feeding. Moreover, the shearing of the nails as they are severed from the strip leaves a ragged edge that assists in providing good holding power. The manufacturing process and the equipment are susceptible of producing nail strips having a high degree of uniformity of nail dimensioning and configuration, aspects that are important in good magazine feeding and power driving. The interconnection between the individual nails may be made as strong as desired to ensure against the strips being inadvertently broken and individual nails being misaligned, while on the other end of the acale, the sheer strength of the interconnecting webs may be such as to conform with the power requirements of the driver and may therefore be of relatively low magnitude.

The embodiments of the invention described above are intended to be merely exrmplary, and those skilled in the art will be able to make numerous variations and modifications of them without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as defined in the appended claims.

I claim:

1. Apparatus for manufacturing a nail strip from an elongated blank of durable material, the elongated blank being of uniform cross-section in all planes taken substantially perpendicular to the longitudinal axis of the elongated blank and the blank having in each said cross-section an elongated shank portion, a tip portion at one end of the shank portion and an enlarged head portion at the other end of the shank portion and the blank including opposite major surfaces, said apparatus comprising means for guiding and holding the blank including members engageable with portions of said opposite major surfaces of the blank of substantial length, said portions of said opposite major surfaces being on either side of a forming position, a pair of cutting and forming dies mounted for movement along a plane at the forming position that is substantially perpendicular to the axis of the blank as it is positioned in the guiding and holding means, each cutting and forming die including a first wedge-shaped cutting and forming portion defined by a first pair of mutually angularly related faces and adapted to cut and form a groove in the shank and tip portion of the blank and a second wedgeshaped cutting and forming portion defined by a second pair of mutually angularly related faces and adapted to form a groove in the head portion of the blank, the included angle between the pair of faces of the first wedge-shaped portion of each die being substantially greater than the included angle between the pair of faces of the second wedge-shaped portion, and means for moving the dies toward and away from each other and into and out of the surfaces of the blank in in-phase relation to each other.

2. Apparatus according to claim 1 wherein the leading edges of the cutting and forming portions of the dies are radiussed, thereby to preclude cutting completely through the blank even though the dies do not come together at the point of closest approach to one another. l 1 

1. Apparatus for manufacturing a nail strip from an elongated blank of durable material, the elongated blank being of uniform cross-section in all planes taken substantially perpendicular to the longitudinal axis of the elongated blank and the blank having in each said cross-section an elongated shank portion, a tip portion at one end of the shank portion and an enlarged head portion at the other end of the shank portion and the blank including opposite major surfaces, said apparatus comprising means for guiding and holding the blank including members engageable with portions of said opposite major surfaces of the blank of substantial length, said portions of said opposite major surfaces being on either side of a forming position, a pair of cutting and forming dies mounted for movement along a plane at the forming position that is substantially perpendicular to the axis of the blank as it is positioned in the guiding and holding means, each cutting and forming die including a first wedgeshaped cutting and forming portion defined by a first pair of mutually angularly related faces and adapted to cut and form a groove in the shank and tip portion of the blank and a second wedge-shaped cutting and forming portion defined by a second pair of mutually angularly related faces and adapted to form a groove in the head portion of the blank, the included angle between the pair of faces of the first wedge-shaped portion of each die being substantially greater than the included angle between the pair of faces of the second wedge-shaped portion, and means for moving the dies toward and away from each other and into and out of the surfaces of the blank in in-phase relation to each other.
 2. Apparatus according to claim 1 wherein the leading edges of the cutting and forming portions of the dies are radiussed, thereby to preclude cutting completely through the blank even though the dies do not come together at the point of closest approach to one another. 